The present invention is generally related to the field of micro electro-mechanical machine (MEMS) based devices.
The ability to detect small displacement is at the heart of many MEMS-based sensors, such as accelerometers, gyroscopes, pressure sensors, acoustic sensors, magnetic sensors, and temperature sensors. In many applications, the detection of a small displacement must be very stable and repeatable. The functionality of many MEMS-based devices is predicated on the design of the support structure which directly affects the mechanical properties of the device. For instance, the support structure used in MEMS-based accelerometers and gyroscopes dictates the mechanical displacement, resonant frequency and stability of the device.
One of the primary limitations of many inertial sensors such as accelerometers and gyroscopes is their stability. In order to increase stability, increased symmetry of the mechanical structure is required and/or the mechanical structure itself must be fabricated in such a way as to increase its stability. The design of the support structure also plays a role in the hysteresis and temperature-dependence of the device. For high performance sensors, such as navigation grade accelerometers and gyroscopes, the stability of the mechanical structure as well as temperature dependence become increasingly important parameters. Highly symmetric structures are desirable for their ability to increase stability and reduce temperature dependence. In addition, if the symmetry can include a dual suspension system, the stability can be increased. A method for fabricating a dual suspension system affords designers greater latitude in the choice of design parameters, results in an overall more robust design, and allows the flexibility to fabricate many different structures including comb-drives, parametric oscillators, and stress-relief structures.
Therefore, there is a current need for a dual-suspension system for MEMS-based devices that provides increased symmetry and stability, as well as a method for fabricating MEMS-based devices having such a dual-suspension system.